Optical characteristics of PtOEP and Ir(ppy)3 triplet-exciton materials for organic electroluminescence devices

Tsuboi, Taijū; Tanigawa, M.

doi:10.1016/s0040-6090(03)00734-x

Cited by 65 publications

(57 citation statements)

References 25 publications

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“…Our relativistic calculations therefore lead us to predict that the MCD signal from Ir(ppy) 3 will be greatly reduced compared to that of Ir(ptz) 3 . The only MCD experiments we are aware of were carried out on a thin film of Ir(ppy) 3 at 15 K under an applied field of 0.84 T. [41] Low-temperature, high-field solution MCD measurements for Ir(ppy) 3 would therefore be an interesting test of our predictions.…”

Section: Analysis Of Spin Mixing Metal-to-ligand Charge Transfer Dementioning

confidence: 94%

Spin–Orbit Coupling in Phosphorescent Iridium(III) Complexes

2011

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We study the excited states of two iridium(III) complexes with potential applications in organic light-emitting diodes: fac-tris(2-phenylpyridyl)iridium(III) [Ir(ppy)(3)] and fac-tris(1-methyl-5-phenyl-3-n-propyl-[1,2,4]triazolyl)iridium(III) [Ir(ptz)(3)]. Herein we report calculations of the excited states of these complexes from time-dependent density functional theory (TDDFT) with the zeroth-order regular approximation (ZORA). We show that results from the one-component formulation of ZORA, with spin-orbit coupling included perturbatively, accurately reproduce both the results of the two-component calculations and previously published experimental absorption spectra of the complexes. We are able to trace the effects of both scalar relativistic correction and spin-orbit coupling on the low-energy excitations and radiative lifetimes of these complexes. In particular, we show that there is an indirect relativistic stabilisation of the metal-to-ligand charge transfer (MLCT) states. This is important because it means that indirect relativistic effects increase the degree to which SOC can hybridise singlet and triplet states and hence plays an important role in determining the optical properties of these complexes. We find that these two compounds are remarkably similar in these respects, despite Ir(ppy)(3) and Ir(ptz)(3) emitting green and blue light respectively. However, we predict that these two complexes will show marked differences in their magnetic circular dichroism (MCD) spectra.

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Section: Analysis Of Spin Mixing Metal-to-ligand Charge Transfer Dementioning

confidence: 94%

Spin–Orbit Coupling in Phosphorescent Iridium(III) Complexes

2011

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“…However, the triplet energy can be measured quite accurately in experiment from the phosphorescence spectra. The largest peak in the phosphorescence spectrum determines the energy of the triplet state, and can be determined with high accuracy [3,[73][74][75][76][77][78][79][80][81][82]. Nevertheless, in contrast to the triplet state, the experimental determination of the singlet energy is very difficult.…”

Section: A Ir(ppy)3mentioning

confidence: 99%

“…One could in principle measure the onset of optical absorption of singlet excitons for this purpose. However, due to strong spin-orbit coupling, the optical absorption starts at much lower energies than the actual singlet energy, leaving a long tail that extends deeply into the high-wavelength region [77][78][79][80][81][82][83]. Another possibility is to determine the strongest peaks in the absorption spectra, which would yield much higher singlet-state energies than the lowest one.…”

Section: A Ir(ppy)3mentioning

confidence: 99%

Role of electronic localization in the phosphorescence of iridium sensitizing dyes

Himmetoḡlu

Marchenko

Dabo³

et al. 2012

The Journal of Chemical Physics

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In this work we present a systematic study of three representative iridium dyes, namely, Ir(ppy)3, FIrpic and PQIr, which are commonly used as sensitizers in organic optoelectronic devices. We show that electronic correlations play a crucial role in determining the excited-state energies in these systems, due to localization of electrons on Ir d orbitals. Electronic localization is captured by employing hybrid functionals within time-dependent density-functional theory (TDDFT) and with Hubbard-model corrections within the ∆-SCF approach. The performance of both methods are studied comparatively and shown to be in good agreement with experiment. The Hubbard-corrected functionals provide further insight into the localization of electrons and on the charge-transfer character of excited-states. The gained insight allows us to comment on envisioned functionalization strategies to improve the performance of these systems. Complementary discussions on the ∆-SCF method are also presented in order to fill some of the gaps in the literature.

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“…The EL characteristic of platinum octaethyl porphine (PtOEP) has been studied together with the phosphorescent molecule Ir(ppy) 3 mostly by Forrest group [3][4][5][6][7][8][9][10]. A sharp EL band with a peak at about 650 nm is observed in the multi-layer structure OLED devices with an emitting layer of PtOEP doped in host molecules such as 4,4 0 -N,N 0 -dicarbazole-biphenyl (CBP).…”

Section: Introductionmentioning

confidence: 99%